Hello! Sorry this answer is a bit late.

The simple answer is that Western education systems just aren’t built to support foreign history in this vein. There’s hundreds, thousands even, of great philosophers I’ll elaborate on below. But know that this isn’t ignorance; this is just how our society has taught us. Two major factors play into this:

• If I asked the average person on the street about the complexities of Nahua philosophy, some even might question what a Nahua is at all. A similar standard exists in other foreign cultures, even if to a lesser degree.
• Most people could tell me who Socrates and Aristotle are, or Kant and Marx. But could you tell me about the revelations of Duns Scotus? The Venerable Bede? Albertus Magnus? These are all famous Medieval European philosophers, surely you should know of them. Apply that line of thinking to Mao Zedong and Confucius being so well known.

For now, I’ll be explaining philosophy from Han to Qing, since you seem to be more familiar with philosophy before and after that long period. This will be organized by schools, though it’s also roughly chronological. Most of this information is taken from Feng Youlan’s History of Chinese Philosophy, but keep in mind it is very abridged and will be skipping over a lot of context. For every philosopher I name, there’s almost definitely several dozen major figures of the same school I didn’t mention. 

New and Old Texts

To start, most (like actually maybe a quarter of) people would be able to tell you that Confucianism only became Chinese orthodoxy during the Han, in contrast to its many venerable rivals in Mohism, Legalism, and others. But what fewer people would be able to tell you was that this change was driven largely by one man: Dong Zhongshu, or 董仲舒.

Dong’s goal as a civil official was to create a guiding ethic for the newly united state to take action. He believed that humanity was a part of Heaven (天), and thus needed to determine its actions by the behavior of that greater authority. In the process of trying to create this system of ethics, he united many previously disparate doctrines from Taoism, the Yin-Yang school, and Confucianism. Not only that, but he had time to create the prototypical form of what would eventually become civil exams during the Sui.

Besides Dong Zhongshu, there were also great philosophers in Yang Xiong (揚雄) and Wang Chong (王充). Both were members of the Old Text school, a branch of Confucianism that claimed to have continuity to the Warring States philosophers themselves, as opposed to the New Text school, including Dong Zhongshu, who created new classics contemporary with the Han itself.

Yang Xiong was known to be the more traditionalist of the two Old Text philosophers. He developed the idea that *Dao* (到), the supreme energy that permeated the universe, was built on the change of reversal, an idea previously espoused in the *Daodejing* and Book of Changes themselves. His work praised Mengzi’s older philosophy while attacking the Yin-Yang school, which is distinct from Daoism, though people often confuse them. Meanwhile, Wang Chong, even being a conservative, was a skepticist and iconoclast, even in one essay saying that the entirety of Confucius’s Analects could be simplified into a single phrase, “with undepreaved thoughts.” His most famous quote, however, is undoubtedly, “In things, there is nothing more manifest than results, and in arguments, there is nothing more manifest than evidence.” 

Both launched heavy criticism of Dong Zhongshu’s ideas that man was a part of Heaven. Wang, for example, pointed out that neither the human nor the fly could affect the ether that flowed through all things. Their work would purge Confucian texts of their influence from the Yin-Yang school entirely.

Neo-Daoism

The great disunity of the Chinese empire in 220 also launched a great disunity in Chinese philosophy. New ways of thinking were constructed. The foreign faith of Buddhism arrived on Han doorways. Even some old schools, long ignored during the previous dynasty, received revival.

To start, Daoism morphed into Neo-Daoism, Xuanxue (玄學), literally “dark learning.” This evolution was mediated by increased interest in the old School of Names, a Warring States school notable for its study of paradoxes, which would become the foundation for iconoclastic thought throughout the period. For example, Neo-Daoists launched a reinterpretation of Kongzi at the expense of Laozi and Zhuangzi. They believed that Kongzi didn’t need to have no desire, because he had already discarded the desire not to have any desire. This kind of paradoxical thinking was one that could have only come about from the School of Names.

The pre-eminent philosopher of Neo-Daoism was the scholar Guo Xiang, or 郭象. He helped pioneer the concept of “pure conversation,” effectively, extremely abstract conversation conducted with pure logic, often causing paradoxes (this is dark learning, after all, it isn’t given credit for clarity). His most famous work, Commentaries on Zhuangzi, however, was accused of being plagiarized from an earlier scholar, Xiang Xiu. Nowadays we know that it’s more likely he amended the earlier work of his contemporary.

This Commentaries was probably the most important work produced during this time. It launched the idea that the Dao itself was “nothing.” It’s rather heady, but it wrote that because the Dao was not a thing, and thus unnameable, it was nothing. Because it was everything, it was nothing. This was the most important of dozens of revelations and developments on Zhuangzi’s older works, which would pave the way for almost all later thought on his philosophy. So influential was this work, that a later monk even once claimed, “People say it was Guo Xiang that wrote a commentary on Zhuangzi. I would say it was Zhuangzi that wrote a commentary on Guo Xiang.”

The philosophy build on the foundation of Commentaries later developed into the doctrine of fengliu (風流), or sentimentalism. This was a sort of Chinese romanticism, emphasizing beauty and living through impulse. In contrast to Western romantic traditions, though, was that sentimentalism viewed sexuality as pure aesthetic, instead of sensual. An exemplar of these sentimentalists was Wang Bi (王弼), whose philosophy can be encompassed by the idea that one can have emotion without being ensnared by them, as often thought impossible by older philosophers.